Resource Concern Thresholds

AQRV Type: VISIBILITY

Sensitive Receptor

Sensitive Receptor Indicator

Thresholds

Natural Visibilty

In specific Class I areas to maintain consistency with Regional Haze implementation plans or BART, the visibility threshold for concern is not exceeded if the 98th %ile change in light extinction is <5% for each year modeled, when compared to the 20% best natural background values.

Natural Visibilty

For sources generally further than 50 km from a Class I area, the visibility threshold for concern is not exceeded if the 98th %ile change in light extinction is <5% for each year modeled, when compared to the annual average natural condition value for that Class I area.

Plume Blight

Absolute Contrast

For near field sources (within 50 km of a Class I area), no additional analysis will be requested If screening analysis of a new or modified source can demonstrate that its emissions will not cause a plume with hourly estimates of DeltaE (color difference index) greater than or equal to 2.0 or the absolute value of the contrast greater than or equal to 0.05 when modeled against natural conditions.

Plume Blight

Absolute Contrast

Higher level near-field screening and refined analysis: no further analysis will likely be requested if a new or modified source can show that impacts from a new or modified source will stay with the threshold of DeltaE <1.0 and |C| <0.02 modeled against natural conditions.

Plume Blight

Color Difference Index

Plume blight near-field refined analysis: no further analysis will likely be requested if a new or modified source can show that impacts from a new or modified source will stay with the threshold of DeltaE <1.0 and |C| <0.02 when modeled against natural conditions.

Plume Blight

Color Difference Index

For near field sources (within 50 km of a Class I area), no additional analysis will be requested If screening analysis of a new or modified source can demonstrate that its emissions will not cause a plume with hourly estimates of DeltaE (color difference index) greater than or equal to 2.0 or the absolute value of the contrast greater than or equal to 0.05 when modeled against natural conditions.

AQRV Type: WATER

Sensitive Receptor

Sensitive Receptor Indicator

Thresholds

Lakes with Low Anc

Acid Neutralizing Capacity

For lakes with low acid neutralizing capacity, the condition class of "Severe Deterioration" applies if there is deterioration below ANC of 0 ueq/l.

Lakes with Low Anc

Acid Neutralizing Capacity

For lakes with low acid neutralizing capacity, the condition class of not significant applies if there is less than a 20% decline in ANC.

Lakes with Low Anc

Acid Neutralizing Capacity

For lakes with low acid neutralizing capacity, the condition class of "Significant Deterioration" applies if there is greater than or equal to a 20% decline in ANC.

Lakes with Low Anc

pH

For lakes with low acid neutralizing capacity, the condition class of "Severe Deterioration" applies if pH levels are below 5.3.

Lakes with Low Anc

pH

For lakes with low acid neutralizing capacity, the condition class of "Significant Deterioration" applies if pH levels are between 5.3-6.0.

Lakes with Low Anc

pH

For lakes with low acid neutralizing capacity, the condition class of "Not Significant" applies if pH levels are above 6.0.

Streams

Acid Neutralizing Capacity

For streams that have an initial acid neutralizing capacity of greater than 100 ueq/l, the condition class of "Significant Deterioration" applies if ANC levels are between 15-25 ueq/l.

Streams

Acid Neutralizing Capacity

For streams that have an initial acid neutralizing capacity of 25-100 ueq/l, the condition class of "Not Significant" applies if there is less than a 25% change in ANC from baseline.

Streams

Acid Neutralizing Capacity

For streams that have an initial acid neutralizing capacity of 25-100 ueq/l, the condition class of "Significant Deterioration" applies if ANC levels are between 15-25 ueq/l.

Streams

Acid Neutralizing Capacity

For streams that have an initial acid neutralizing capacity of less than 25 ueq/l, the condition class of "Not Significant" applies if there is no change from baseline.

Streams

Acid Neutralizing Capacity

For streams that have an initial acid neutralizing capacity of greater than 100 ueq/l, the condition class of "Not Significant" applies if there is less than a 50% change in ANC from baseline.

Streams

Acid Neutralizing Capacity

For streams that have an initial acid neutralizing capacity of less than 25 ueq/l, the condition class of "Significant Deterioration" applies if there is any change from baseline.

Streams

Acid Neutralizing Capacity

For streams that have an initial acid neutralizing capacity of 25-100 ueq/l, the condition class of "Severe Deterioration" applies if ANC levels are less than 15 ueq/l.

Streams

Acid Neutralizing Capacity

For streams that have an initial acid neutralizing capacity of less than 25 ueq/l, the condition class of "Severe Deterioration" applies if there is any change from baseline.

Streams

Acid Neutralizing Capacity

For streams that have an initial acid neutralizing capacity of greater than 100 ueq/l, the condition class of "Severe Deterioration" applies if ANC levels are less than 15 ueq/l.

Pollutant Exposure Concern Thresholds

Pollutant Exposures

Level Name

Thresholds

N

EXCEEDANCE

The Deposition Analysis Threshold for nitrogen deposition is 0.010 kg/ha/yr. Below this, estimated impacts from a source greater than 50km from a FLM Class I Area are considered negligible.

Q

QOverD

For new or modified sources locating greater than 50 km from a Class I area, its impacts will be considered negligible with respect to Class I AQRVs if its total SO2, NOx, PM10, and H2SO4 annual emissions in tons/yr, based on 24-hr maximum allowable emissions, divided by the distance (km ) from the Class I area (Q/D) is 10 or less. For sources operating less than a year, the emissions must be adjusted to reflect what the emissions would be if the source operated year-round.

S

EXCEEDANCE

The Deposition Analysis Threshold for sulfur deposition is 0.005 kg/ha/yr. Below this, estimated impacts from a source greater than 50km from a FLM Class I Area are considered negligible.